It is a well known phenomenon ...

It is a well known phenomenon that the same amateur who can conduct the middle game quite creditably, is usually perfectly helpless in the end game. One of the principal requisites of good chess is the ability to treat both the middle and end game equally well.
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 Aron Nimzowitsch

Quotes from the same author

The beauty of a move lies not in its appearance but in the thought behind it.
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 Aron Nimzowitsch
How is it to be explained that something inside me revolts against the playing of obvious moves? Perhaps we may perceive the underlying reason in the fact that I derive satisfaction from seeking to reveal the concealed meaning of a position by means of maneuvering play and therefore I do not wish to see this satisfaction curtailed by a banal, more or less fortuitous decision. Naturally, this phenomenon is played out beneath the threshold of consciousness. The waking consciousness will, of course, in each individual case, give preference to the more rapid means of deciding the game.
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 Aron Nimzowitsch
When I today ask myself whence I got the moral courage, for it takes moral courage to make a move (or form a plan) running counter to all tradition, I think I may say in answer, that it was only my intense preoccupation with the problem of the blockade which helped me to do so.
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 Aron Nimzowitsch
Do not always be thinking of attack! Moves that safeguard your position are often far more prudent.
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 Aron Nimzowitsch